compiler-rt/lib/profile/InstrProfilingPlatformAIX.c

   1 /*===- InstrProfilingPlatformAIX.c - Profile data AIX platform ------------===*\
   2 |*
   3 |* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 |* See https://llvm.org/LICENSE.txt for license information.
   5 |* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 |*
   7 \*===----------------------------------------------------------------------===*/
   8
   9 #if defined(_AIX)
  10
  11 #ifdef __64BIT__
  12 #define __XCOFF64__
  13 #endif
  14 #include <errno.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <sys/ldr.h>
  18 #include <xcoff.h>
  19
  20 #include "InstrProfiling.h"
  21 #include "InstrProfilingInternal.h"
  22
  23 #define BIN_ID_PREFIX "xcoff_binary_id:"
  24
  25 // If found, write the build-id into the Result buffer.
  26 static size_t FindBinaryId(char *Result, size_t Size) {
  27   unsigned long EntryAddr = (unsigned long)__builtin_return_address(0);
  28
  29   // Use loadquery to get information about loaded modules; loadquery writes
  30   // its result into a buffer of unknown size.
  31   char Buf[1024];
  32   size_t BufSize = sizeof(Buf);
  33   char *BufPtr = Buf;
  34   int RC = -1;
  35
  36   errno = 0;
  37   RC = loadquery(L_GETXINFO | L_IGNOREUNLOAD, BufPtr, (unsigned int)BufSize);
  38   if (RC == -1 && errno == ENOMEM) {
  39     BufSize = 64000; // should be plenty for any program.
  40     BufPtr = malloc(BufSize);
  41     if (BufPtr != 0)
  42       RC = loadquery(L_GETXINFO | L_IGNOREUNLOAD, BufPtr, (unsigned int)BufSize);
  43   }
  44
  45   if (RC == -1)
  46     goto done;
  47
  48   // Locate the ld_xinfo corresponding to this module.
  49   struct ld_xinfo *CurInfo = (struct ld_xinfo *)BufPtr;
  50   while (1) {
  51     unsigned long CurTextStart = (uint64_t)CurInfo->ldinfo_textorg;
  52     unsigned long CurTextEnd = CurTextStart + CurInfo->ldinfo_textsize;
  53     if (CurTextStart <= EntryAddr && EntryAddr < CurTextEnd) {
  54       // Found my slot. Now search for the build-id.
  55       char *p = (char *)CurInfo->ldinfo_textorg;
  56
  57       FILHDR *f = (FILHDR *)p;
  58       AOUTHDR *a = (AOUTHDR *)(p + FILHSZ);
  59       SCNHDR *s =
  60           (SCNHDR *)(p + FILHSZ + f->f_opthdr + SCNHSZ * (a->o_snloader - 1));
  61       LDHDR *ldhdr = (LDHDR *)(p + s->s_scnptr);
  62       // This is the loader string table
  63       char *lstr = (char *)ldhdr + ldhdr->l_stoff;
  64
  65       // If the build-id exists, it's the first entry.
  66       // Each entry is comprised of a 2-byte size component, followed by the
  67       // data.
  68       size_t len = *(short *)lstr;
  69       char *str = (char *)(lstr + 2);
  70       size_t PrefixLen = sizeof(BIN_ID_PREFIX) - 1;
  71       if (len > PrefixLen && (len - PrefixLen) <= Size &&
  72           strncmp(str, BIN_ID_PREFIX, PrefixLen) == 0) {
  73         memcpy(Result, str + PrefixLen, len - PrefixLen);
  74         RC = len - PrefixLen;
  75         goto done;
  76       }
  77       break;
  78     }
  79     if (CurInfo->ldinfo_next == 0u)
  80       break;
  81     CurInfo = (struct ld_xinfo *)((char *)CurInfo + CurInfo->ldinfo_next);
  82   }
  83 done:
  84   if (BufSize != sizeof(Buf) && BufPtr != 0)
  85     free(BufPtr);
  86   return RC;
  87 }
  88
  89 static int StrToHexError = 0;
  90 static uint8_t StrToHex(char c) {
  91   if (c >= '0' && c <= '9')
  92     return c - '0';
  93   if (c >= 'a' && c <= 'f')
  94     return c - 'a' + 0xa;
  95   if (c >= 'A' && c <= 'F')
  96     return c - 'A' + 0xa;
  97   StrToHexError = 1;
  98   return 0;
  99 }
 100
 101 COMPILER_RT_VISIBILITY int __llvm_write_binary_ids(ProfDataWriter *Writer) {
 102   // 200 bytes should be enough for the build-id hex string.
 103   static char Buf[200];
 104   // Profile reading tools expect this to be 8-bytes long.
 105   static int64_t BinaryIdLen = 0;
 106   static uint8_t *BinaryIdData = 0;
 107
 108   // -1 means we already checked for a BinaryId and didn't find one.
 109   if (BinaryIdLen == -1)
 110     return 0;
 111
 112   // Are we being called for the first time?
 113   if (BinaryIdLen == 0) {
 114     if (getenv("LLVM_PROFILE_NO_BUILD_ID"))
 115       goto fail;
 116
 117     int BuildIdLen = FindBinaryId(Buf, sizeof(Buf));
 118     if (BuildIdLen <= 0)
 119       goto fail;
 120
 121     if (Buf[BuildIdLen - 1] == '\0')
 122       BuildIdLen--;
 123
 124     // assume even number of digits/chars, so 0xabc must be 0x0abc
 125     if ((BuildIdLen % 2) != 0 || BuildIdLen == 0)
 126       goto fail;
 127
 128     // The numeric ID is represented as an ascii string in the loader section,
 129     // so convert it to raw binary.
 130     BinaryIdLen = BuildIdLen / 2;
 131     BinaryIdData = (uint8_t *)Buf;
 132
 133     // Skip "0x" prefix if it exists.
 134     if (Buf[0] == '0' && Buf[1] == 'x') {
 135       BinaryIdLen -= 1;
 136       BinaryIdData += 2;
 137     }
 138
 139     StrToHexError = 0;
 140     for (int i = 0; i < BinaryIdLen; i++)
 141       BinaryIdData[i] = (StrToHex(BinaryIdData[2 * i]) << 4) +
 142                         StrToHex(BinaryIdData[2 * i + 1]);
 143
 144     if (StrToHexError)
 145       goto fail;
 146
 147     if (getenv("LLVM_PROFILE_VERBOSE")) {
 148       char *StrBuf = (char *)COMPILER_RT_ALLOCA(2 * BinaryIdLen + 1);
 149       for (int i = 0; i < (int)BinaryIdLen; i++)
 150         sprintf(&StrBuf[2 * i], "%02x", BinaryIdData[i]);
 151       PROF_NOTE("Writing binary id: %s\n", StrBuf);
 152     }
 153   }
 154
 155   uint8_t BinaryIdPadding = __llvm_profile_get_num_padding_bytes(BinaryIdLen);
 156   if (Writer && lprofWriteOneBinaryId(Writer, BinaryIdLen, BinaryIdData,
 157                                       BinaryIdPadding) == -1)
 158     return -1; // Return -1 rather goto fail to match the NT_GNU_BUILD_ID path.
 159
 160   return sizeof(BinaryIdLen) + BinaryIdLen + BinaryIdPadding;
 161
 162 fail:
 163   if (getenv("LLVM_PROFILE_VERBOSE"))
 164     fprintf(stderr, "no or invalid binary id: %.*s\n", (int)sizeof(Buf), Buf);
 165   BinaryIdLen = -1;
 166   return 0;
 167 }
 168
 169 // Empty stubs to allow linking object files using the registration-based scheme
 170 COMPILER_RT_VISIBILITY
 171 void __llvm_profile_register_function(void *Data_) {}
 172
 173 COMPILER_RT_VISIBILITY
 174 void __llvm_profile_register_names_function(void *NamesStart,
 175                                             uint64_t NamesSize) {}
 176
 177 // The __start_SECNAME and __stop_SECNAME symbols (for SECNAME \in
 178 // {"__llvm_prf_cnts", "__llvm_prf_data", "__llvm_prf_name", "__llvm_prf_vnds"})
 179 // are always live when linking on AIX, regardless if the .o's being linked
 180 // reference symbols from the profile library (for example when no files were
 181 // compiled with -fprofile-generate). That's because these symbols are kept
 182 // alive through references in constructor functions that are always live in the
 183 // default linking model on AIX (-bcdtors:all). The __start_SECNAME and
 184 // __stop_SECNAME symbols are only resolved by the linker when the SECNAME
 185 // section exists. So for the scenario where the user objects have no such
 186 // section (i.e. when they are compiled with -fno-profile-generate), we always
 187 // define these zero length variables in each of the above 4 sections.
 188 static int dummy_cnts[0] COMPILER_RT_SECTION(
 189     COMPILER_RT_SEG INSTR_PROF_CNTS_SECT_NAME);
 190 static int dummy_bits[0] COMPILER_RT_SECTION(
 191     COMPILER_RT_SEG INSTR_PROF_BITS_SECT_NAME);
 192 static int dummy_data[0] COMPILER_RT_SECTION(
 193     COMPILER_RT_SEG INSTR_PROF_DATA_SECT_NAME);
 194 static const int dummy_name[0] COMPILER_RT_SECTION(
 195     COMPILER_RT_SEG INSTR_PROF_NAME_SECT_NAME);
 196 static int dummy_vnds[0] COMPILER_RT_SECTION(
 197     COMPILER_RT_SEG INSTR_PROF_VNODES_SECT_NAME);
 198
 199 // To avoid GC'ing of the dummy variables by the linker, reference them in an
 200 // array and reference the array in the runtime registration code
 201 // (InstrProfilingRuntime.cpp)
 202 #ifdef __GNUC__
 203 #pragma GCC diagnostic push
 204 #pragma GCC diagnostic ignored "-Wcast-qual"
 205 #endif
 206 COMPILER_RT_VISIBILITY
 207 void *__llvm_profile_keep[] = {(void *)&dummy_cnts, (void *)&dummy_bits,
 208                                (void *)&dummy_data, (void *)&dummy_name,
 209                                (void *)&dummy_vnds};
 210 #ifdef __GNUC__
 211 #pragma GCC diagnostic pop
 212 #endif
 213 #endif